Locking mechanism and image forming apparatus equipped with locking mechanism

A locking mechanism comprising:

• a cover member openable and closable by pivotally moving about a first edge of the cover member as a fulcrum;
• a shaft member extending along a second edge of the cover member opposed to the first edge of the cover member and rotatably supported at both ends by the cover member;
• a hook member coupled unitarily rotatably to the shaft member and having an engageable hook portion formed at a distal end thereof;
• an engageable counterpart capable of locking the cover member by engaging with the engageable hook portion of the hook member when the cover member moves to a closed position;
• a torsion coil spring biasing the hook member toward a locking position of the cover member where the engageable hook portion engages with the engageable counterpart;
• and
• a manually operable portion capable of being manually operated with the cover member in the closed position to rotate the shaft member to disengage the engageable hook portion from the engageable counterpart,
• the cover member comprising:
• a fittable recess that opens in a direction orthogonal to an axis of the shaft member, receives the torsion coil spring, and fits the torsion coil spring inside such that an outer periphery of the torsion coil spring contacts the inside of the fittable recess;
• and
• an anchoring counter element to which one end of the torsion coil spring is anchored,
• wherein the torsion coil spring is engaged with the hook member while being fitted in the fittable recess, thus biasing the hook member toward movement about the axis of the shaft member to the locking position and supporting both the ends of the shaft member rotatably around an internal surface of the torsion coil spring.